Gastouni (Greek: Γαστούνη) is a town and a former municipality in Elis, West Greece, Greece. Since the 2011 local government reform it is part of the municipality Pineios, of which it is the seat and a municipal unit. The municipal unit has an area of 59.325 km2. Gastouni is situated in a flat rural area, 5 km from the Ionian Sea. The river Pineios flows into the sea near Gastouni. The town is 6 km (4 mi) south of Andravida, 4 km (2 mi) east of Vartholomio, 11 km (7 mi) northwest of Amaliada and 26 km (16 mi) northwest of Pyrgos. The population of the town proper was 7,485 in 2011. The Greek National Road 9/E55 (Patras - Pyrgos) and the railway from Patras to Pyrgos pass east of Gastouni. There is a 12th-century Byzantine church in the southwestern quarter Katholiki.